Charge-Transfer Spectra and Bonding in Tetrahedral Mn(VI), Cr(V), and V(IV) and Mn(VII), Cr(VI), and V(V) Oxo Anions.
Charge-Transfer Spectra and Bonding in Tetrahedral Mn(VI), Cr(V), and V(IV) and Mn(VII), Cr(VI), and V(V) Oxo Anions.
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四面体 Mn(VI)、Cr(V) 和 V(IV) 以及 Mn(VII)、Cr(VI) 和 V(V) 氧阴离子中的电荷转移光谱和成键。
DOI：
10.1021/ic971014h
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发表时间：
1998
影响因子：
4.6
通讯作者：
C. Daul
中科院分区：
文献类型：
--
作者：
M. Atanasov;T. Brunold;H. Güdel;C. Daul
报告了四面体 Mn(VI)、Cr(V) 和 V(IV)(d(1)) 含氧阴离子在基态和最低激发 d-d 和 O --> M 电荷转移 (CT) 态的密度泛函理论 (DFT) 计算，并通过参考等电子 Mn(VII)、Cr(VI) 和 V(V) (d(0)) 以及 Mn(V) 和 Mn(V) 和 Mn(V) 的光谱来指定电子吸收光谱。 Cr(IV) (d(2)) 阴离子。计算出的电子激发沿完全对称金属配体振动（α（1））的几何位移与从实验电子振动精细结构推导出的数据一致，支持了所提出的任务。使用包含（与DFT不同）构型相互作用（CICT）的CT模型，表明MnO(4)(2)(-)在17 000、23 300和28 200 cm(-)(1)处的CT激发态归因于d(2) (3)A(2)(2e(2))、(1)E(2e(2))和(3)A(2)(2e(2))最终态分别与配体1t(1)和4t(2)轨道上的单孔(L)结合。与 d(2) 系统相比，d(2)L(d(1)) 态较高的 10Dq 和较小的 B 值与金属-配体键的缩短相关，伴随着电子从反键 d 轨道的移除，导致共价性的增加以及 Cr(V) 与 (3)T(2)(2e(1)5t(2)(1))L 的 CT 态排序的变化与具有近简并 (3)T(2)(2e(1)5t(2)(1)) 和 (1)E(2e(2)) 项的 Cr(IV) 相比，(10Dq) 的能量高于 (1)E(2e(2))L (8B + 2C)。这使得人们能够根据 Cr(V)(d(1)) 的 CT (d(2)L) 谱估计 (3)A(2)(2e(2))L --> (1)E(2e(2))L 跃迁的能量，而 Cr(IV) 无法观察到这一点。通过对 V(V)、Cr(VI) 和 Mn(VII) (d(0)) 以及 V(IV)、Cr(V) 和 Mn(VI) (d(1)) 含氧阴离子中最低 CT 带的计算和实验振荡器强度和 Huang-Rhys 因子 (S) 的比较，可以看出，该系列中共价性从左到右的增加伴随着 α(1) 级数中带强度和 S 的减小。振动。提出了根据离子对金属-配体键的贡献从 Mn(VI) 增加到 Cr(V) 和 V(IV) 的结果来解释这一结果。 “d-d”跃迁的强度显示出相反的趋势；增加共价导致 d --> d 和 CT 激发态之间更强的混合，从而增加强度。
Density functional theory (DFT) calculations on the tetrahedral Mn(VI), Cr(V), and V(IV)(d(1)) oxo anions in their ground and lowest excited d-d and O --> M charge transfer (CT) states are reported and used to assign the electronic absorption spectra by reference to the spectra of the isoelectronic Mn(VII), Cr(VI), and V(V) (d(0)) and the Mn(V) and Cr(IV) (d(2)) anions. Calculated geometrical shifts along the totally symmetric metal-ligand vibration (alpha(1)) for electronic excitations are in agreement with data deduced from experimental vibronic fine structures, supporting the proposed assignments. Using a CT model including (as different from DFT) configuration interaction (CICT), it is shown that the CT excited states of MnO(4)(2)(-) at 17 000, 23 300, and 28 200 cm(-)(1) are due to d(2) (3)A(2)(2e(2)), (1)E(2e(2)), and (3)A(2)(2e(2)) final states combining with a single hole (L) on the ligand 1t(1) and 4t(2) orbitals, respectively. The higher 10Dq and smaller B values for the d(2)L(d(1)) states compared to those of the d(2) systems correlate with the shortening of the metal-ligand bond accompanying the removal of electrons from the antibonding d orbitals, leading to an increase in covalency and a change in the ordering of CT states for Cr(V) with (3)T(2)(2e(1)5t(2)(1))L (10Dq) at a higher energy than (1)E(2e(2))L (8B + 2C) as compared to Cr(IV) with nearly degenerate (3)T(2)(2e(1)5t(2)(1)) and (1)E(2e(2)) terms. This allows one to estimate the energy of the (3)A(2)(2e(2))L --> (1)E(2e(2))L transition from the CT (d(2)L) spectrum of Cr(V)(d(1)), which could not be observed for Cr(IV). From a comparison of calculated and experimental oscillator strengths and Huang-Rhys factors (S) for the lowest CT band in the V(V), Cr(VI), and Mn(VII) (d(0)) and the V(IV), Cr(V), and Mn(VI) (d(1)) oxo anions, it is shown that the increase in covalency from left to right in this series is accompanied by a reduction in band intensity and S for the progression in the alpha(1) vibration. An explanation of this result in terms of ionic contributions to the metal-ligand bond increasing from Mn(VI) to Cr(V) and V(IV) is proposed. Intensities of "d-d" transitions display the opposite trend; increasing covalency leads to stronger mixing between d --> d and CT excited states and thus an increase in intensity.